in my experience (up to 6000m+) - only propane-butane mix (mixed with isobutane if it is hardly freezing).in temperatures below -5C common p-b mix has tendency to decrease its resilience, so the fire becomes smaller (it is easy to enhance the fire for a few minutes - just shake the stove). but you don't have problems with inflaming/exploding/controlling the fire like in the case of other liquid fuel (petrol/alcohol/parafin oil). for the heights of pamir highway common p-b mix like karrimor/epigas/coleman/primus/etc. is ok.

Aaaaand... Dushanbe is out of gas canisters. When will new canisters appear? God only knows. Try to buy in Bishkek or Khorog(maybe?) or elsewhere first. Maybe in Osh, but when I was in Osh this year a hostel manager was asking travellers if they had any used canisters they wanted to sell to him so that he could resell. If they were available at the bazaar he would have a stack of them.

What to do? Call the hostels in Dushanbe and ask (City Hostel, Green House and Yellow House first).

I asked a woman in Panjakent and she said, there is a availability (a shop) to buy gas cartridges. The woman is very helpful. You can ask here for the address. The contact details below. Maybe you have to write in Russian... I want to buy cartridges in Tashkent. Panjakent is the second option.